There is an ongoing effort to identify and develop new herbicides, particularly naturally occurring substances having root retardant activity. However, the identification of commercially viable retardants from abundant natural resources has proven to be rather difficult. Some active compounds derived from natural sources have been identified. For example, U.S. Pat. No. 5,290,749 (“the '749 patent”) describes the use of corn protein hydrolysates, which are produced by enzymatic hydrolysis of corn gluten meal, for inhibiting the germination of weeds. U.S. Pat. No. 5,290,757 (“the '757 patent”) describes various dipeptides as having herbicidal activity. These applications have not been commercially exploited, however, possibly due to the apparent high cost per active dose that would be required to for commercially viable applications. The successful commercialization of non-toxic, natural materials for such applications requires a large, inexpensive, readily available source of the active agent.
Corn gluten meal, an insoluble product obtained from the processing of corn, is presently marketed as a root retardant, and is described in U.S. Pat. No. 5,030,268. However, the herbicidal potency of corn gluten meal per unit weight of solids is relatively weak, requiring the application of a somewhat large quantity of the material relative to the medium in order to achieve desirable herbicidal efficacy. As such, there is a need for more potent, non-toxic, commercially viable natural materials.
One industry in which a particular need for cost-effective naturally produced herbicides is found in the brewing industry. Generally, beer and other fermentable beverages are prepared by malting a fermentable grain (often barley) and subsequently fermenting the malted grain. During the malting step, enzymes in the grain cause the breakdown of other components of the grain into maltose. Usually, however, the malting of the grain undesirably causes emergent growth of rootlets from the grain. The rootlets thus generated generally must be removed prior to fermentation, thus requiring additional processing costs and adversely affecting yields. The malting techniques known in the art are not satisfactory in inhibiting rootlet growth prior to fermentation.
In light of the foregoing, it is a general object of the invention to provide a root retardant. In some embodiments, it is an object to provide a malting composition that includes a root retardant and a maltable grain. The present invention provides such herbicides and methods of using them. These and other advantages of the present invention, as well as additional inventive features, will be apparent from the description of the invention provided herein.